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US gallons to litres

Multiply US gallons by 3.7854 to get litres.

1 gal = 3.7854 LNIST HB 44 · BIPM SI
gal
37.8541L

10 gal = 37.8541 L

How to convert US gallons to litres

The litre is a cubic decimetre (0.001 m³), the SI-accepted metric unit of volume. The US gallon is the US liquid gallon, exactly 231 cubic inches (3.785411784 litres).

Worked example — 10 gal: 10 × 3.7854 = 37.8541 L.

US gallons to litres table

Common conversions. The reverse table is on litres to US gallons.
US gallonsLitres
1 gal3.7854 L
2 gal7.5708 L
3 gal11.3562 L
5 gal18.9271 L
10 gal37.8541 L
15 gal56.7812 L
20 gal75.7082 L
50 gal189.2706 L
100 gal378.5412 L

Reverse and related

About US gallons and litres

US gallon (gal)

1 gal = 3.7854 L

Definition. The US liquid gallon, exactly 231 cubic inches (3.785411784 litres)

History and origin

The US gallon derives from the old English wine gallon of 231 cubic inches, a value the United States kept when Britain moved to a larger imperial gallon in 1824. It equals exactly 3.785411784 litres.

Current use

The gallon is the everyday US unit for fuel, milk and paint; the imperial gallon used in the UK and Canada is about 20 percent larger.

Source: NIST Handbook 44, Appendix C §2 (U.S. Customary Units) and §5 (Tables of Equivalents)

Litre (L)

1 L = 0.264172 gal

Definition. A cubic decimetre (0.001 m³), the SI-accepted metric unit of volume

History and origin

The litre was introduced in France in 1795 as a unit of volume, defined as one cubic decimetre. It is not an SI base unit but is accepted for use with the SI.

Current use

Litres measure drinks and bottles, fuel and engine sizes across the metric world, and appear on beverage containers almost everywhere.

Source: BIPM SI Brochure (2019); the litre is an SI-accepted unit (1 L = 1 dm³)

Where people use this

US gallons: fuel in the US, large containers, paint. Litres: drinks and bottles, fuel, engine sizes. 1 US gallon is about 3.79 L.

How we know this is right
The factor is fixed by the standards that define the units, not chosen — so it is exact, not a measurement:
1 L = 0.2641720524 gal, so 1 gal = 1 ÷ 0.2641720524 = 3.7854 L.

Every value is carried to full double precision; the display is rounded.

Sources: BIPM SI Brochure (2019); the litre is an SI-accepted unit (1 L = 1 dm³); NIST Handbook 44, Appendix C §2 (U.S. Customary Units) and §5 (Tables of Equivalents).

Questions people ask

How many litres is 1 US gallon?

One US gallon is exactly 3.785411784 litres, about 3.79 L. To convert gallons to litres, multiply by 3.785.

How many litres is 5 gallons?

5 US gallons is about 18.9 litres, and 10 gallons is about 37.9 litres.

Is a US gallon the same as a UK gallon?

No. The imperial (UK) gallon is about 4.55 L, roughly 20% larger than the US gallon.

How many litres is a gallon of gas?

A US gallon of fuel is about 3.79 litres.

All US gallon conversions